Unit 3 Electricity & Magnetism- Transistors

1. Unit 3 Electricity & Magnetism-Transistors Physics 5d. Students know the properties of transistors and the role of transistors in electric circuits

2. The Story of the Transistor • Bell Laboratories-originally the research and development arm of the telephone company American Telephone and Telegraph (AT&T) • One of the first pioneering advances of Bell Labs in 1900s was the vacuum tube. • Vacuum tube-amplified faint telephone signals and high speed on-off switch.

3. First computer, 1940-1950

4. Computer 1960’s

5. Computer 1970’s

6. Computer 1980’s

7. Computer 2008

8. First Television, 1930’s

9. TV 1950’s

10. TV 1980’s

11. TV 2011

12. First telephone, 1860’s

13. Telephone 1950’s

14. Telephone 1990’s

15. Telephone 2011

16. What do you notice about these gadgets over time?

17. Theyget smaller!!!!WHY?

18. Because transistors replaced vacuum tubes

19. Practice • Why are modern radios, calculators, and computers much smaller than they were in the past? • A. Modern appliances use less electricity • B. Electricity has become more expensive • C. Vacuum tubes replaced larger transistors • D. Transistors replaced larger vacuum tubes

20. Vacuum Tubes Before transistors came along, vacuum tubes worked as switches and amplifiers. Notice how LARGE they are!

21. Transistors -Much smaller. -Allowed technology to become more compact -Transistors amplify electric signals/currents

22. Transistors • So…what are they? • A semiconductor device used to amplify and switch electronic signals and power. • Are found embedded in integrated circuits (aka microchips) used in computers, mobile phones, digital appliances, etc. • Make modern radios, calculators, computers smaller than before

23. Microchips-in which thousands or millions of transistors are deposited on a piece of silicon

24. Transistor • Are made out of metalloids. • Why?

25. Transistor • Are made out of metalloids. • Why? • Because they have properties of BOTH metals and non-metals • This allows them to be “altered” and manipulated to be more versatile

26. Practice • What makes semiconductors useful in everyday electronic devices? • A. Electrons can flow at any current • B. Electricity is conducted better than by metals • C. Current flow can be resisted better than by insulators • D. Conductivity can be altered by adding other materials.

27. Transistor in drawings

28. The Story of the Transistor Continued… • William Shockley (theoretician) selected Walter Brattain (experimental physicist) and John Bardeen (theoretical physicist) to create a semiconductor amplifier.

29. They did countless tests on different samples of silicon & germanium. • In Dec. 1947, Bardeen and Brattain produced the world’s first semiconductor amplifier: the point-contact transistor

30. The First Transistor

31. Highest Achievement-Nobel Prize • William Shockley, Walter Brattain and John Bardeen shared the 1956 Nobel Prize in Physics.

32. Practice • What is the function of a transistor in an electrical device? • A. Reducing current to prevent overheating • B. Inducing a magnetic field to urn a motor • C. Controlling a large current output to amplify an electric signal • D. Storing an electrical charge that is used as a source of power

33. Practice • Which electrical device is shown in the diagram? • Capacitor • Inductor • Resistor • Transistor

34. Activity 1 • 1. You will be in groups of 3 or 4 • 2. List 5 devices that affect me most • 3. Tell which device is important in your life • 4. Describe how your life would change without each device • 5. Then as a whole, compare & contrast each team’s list

35. Activity 2 • Write an essay on the electronic device that most changed your life.